This invention relates generally to characterizing dispersed matter in a continuous phase and more specifically to a method for in situ characterization of a medium of dispersed matter in a continuous phase.
In fluidized beds, droplet coalescence chambers, well mixed batch reactors, fermentation reactors, and other such systems, it is desirable to characterize the size, distribution, or flow of dispersed matter in the continuous phase contained in the reactor system. A variety of techniques exist in which the dispersed matter is physically removed from the system and sized and sorted using conventional methods. These techniques, however, are invasive, since the act of particle sampling may disturb the size, distribution, or flow characteristics of the dispersed matter and the reactor system. Other methods involve "tracer" techniques in which a subclass of the dispersed matter is altered to facilitate its detection. Examples of these methods include radiolabelling of particles, painting the particles with fluorescent paint, and using particles of a different color or size. These techniques are also considered invasive because the physical characteristics of the dispersed phase are changed. Furthermore, the systems represented by these methods are often specialized cases and do not represent the population size, chemistry, or other characteristics occurring in the actual operating reactors. Because of these deficiencies, current techniques cannot be utilized to monitor operating systems.
Although noninvasive methods are available, they may not be used in systems containing a high dispersed phase content and do not provide fine spatial resolution. For extremely dilute systems (&lt;1%), the dispersed phase may be visualized directly, or light scattering techniques may be employed. Capacitance measurements provide dispersed phase volume fraction in more dense systems, and capacitance imaging has been used to study bubble flow and coalescence in gas fluidized beds. Current capacitance imaging, however, is limited in resolution to objects of the order of 1 cm. Finally, video techniques used to observe particle flow in fluidized beds are also known, but while such techniques provide images at solid volume fractions up to 40%, they have disclosed only macroscopic information and have not been used to characterize individual particles.
Accordingly, a need in the art exists for an in situ method for characterization of a medium of dispersed matter in a continuous phase which is noninvasive, enables direct characterization of dispersed matter in a continuous phase at virtually any volume fraction, and provides fine spatial resolution.